Answer
$7i$
Work Step by Step
Factor the radicand so that one factor is a perfect square while the other factor is $-1$ to obtain:
$=\sqrt{49(-1)}
\\=\sqrt{7^2(-1)}$
Simplify to obtain:
$=7\sqrt{-1}$
RECALL:
$\sqrt{-1} = i$
Use the ruile above to obtain:
$=7i$
